org.eclipse.birt.report.designer.internal.ui.dnd.DesignElementDragAdapter.java Source code

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Here is the source code for org.eclipse.birt.report.designer.internal.ui.dnd.DesignElementDragAdapter.java

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/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.report.designer.internal.ui.dnd;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.birt.report.designer.internal.ui.util.Policy;
import org.eclipse.birt.report.model.api.ThemeHandle;
import org.eclipse.gef.dnd.TemplateTransfer;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;

/**
 * Supports dragging elements in outline view.
 */

public abstract class DesignElementDragAdapter extends DragSourceAdapter {

    private StructuredViewer viewer;

    // added this member to fix bug 116180
    protected List selectionList = new ArrayList();

    /**
     * Constructor
     * 
     * @param viewer
     */
    public DesignElementDragAdapter(StructuredViewer viewer) {
        super();
        this.viewer = viewer;
    }

    /**
     * @see DragSourceAdapter#dragFinished(DragSourceEvent)
     */
    public void dragFinished(DragSourceEvent event) {
        if (event.doit) {
            TemplateTransfer.getInstance().setTemplate(null);
            if (Policy.TRACING_DND_DRAG) {
                System.out.println("DND >> Drag finished."); //$NON-NLS-1$
            }
        }
    }

    /**
     * @see DragSourceAdapter#dragSetData(DragSourceEvent)
     */
    public void dragSetData(DragSourceEvent event) {
        //      IStructuredSelection selection = (IStructuredSelection) getViewer( ).getSelection( );
        //      Object[] objects = selection.toList( ).toArray( );

        // fix bug 116180
        Object[] objects = selectionList.toArray();
        if (TemplateTransfer.getInstance().isSupportedType(event.dataType))
            event.data = objects;
    }

    /**
     * @see DragSourceAdapter#dragStart(DragSourceEvent)
     */
    public void dragStart(DragSourceEvent event) {
        boolean doit = !getViewer().getSelection().isEmpty();
        if (doit) {
            IStructuredSelection selection = (IStructuredSelection) getViewer().getSelection();
            selectionList = selection.toList();
            Object[] objects = selection.toList().toArray();
            if (validateType(objects)) {
                for (int i = 0; i < objects.length; i++)
                    if (!validateTransfer(objects[i])) {
                        doit = false;
                        break;
                    }
            } else
                doit = false;
            if (doit)
                TemplateTransfer.getInstance().setTemplate(objects);
        }
        event.doit = doit;
        if (Policy.TRACING_DND_DRAG && doit) {
            System.out.println("DND >> Drag starts."); //$NON-NLS-1$
        }
    }

    /**
     * Validates every transfer element
     * 
     * @param transfer
     *            every transfer element
     * @return if transfer element can be dragged
     */
    protected abstract boolean validateTransfer(Object transfer);

    /**
     * Validates types of transfer elements.
     * <p>
     * Default implementation is verify all types of transfer elements are same
     * 
     * @param transfer
     *            transfer elements
     * @return type is same or not
     */
    protected boolean validateType(Object transfer) {
        Object[] objects = (Object[]) transfer;
        if (objects.length <= 0) {
            return false;
        }

        // Theme can be draged when only one is selected. Fix bug #151953
        if (objects[0] instanceof ThemeHandle) {
            if (objects.length == 1) {
                return true;
            } else {
                return false;
            }
        }

        // Drag the elements if selected ones are the same type.
        Class type = null;
        for (int i = 0; i < objects.length; i++) {
            if (type == null)
                type = objects[i].getClass();
            else if (!type.equals(objects[i].getClass()))
                return false;
        }
        return true;
    }

    /**
     * Returns viewer
     * 
     * @return viewer
     */
    protected StructuredViewer getViewer() {
        return viewer;
    }
}